Calumetite

Calumetite is a natural rarely occurring mineral. It was discovered in 1963 at the Centennial Mine near Calumet, Michigan, United States. Calumetite was first discovered along with anthonyite. It has a chemical formula of Cu(OH,Cl)2•2(H2O).
History
Calumetite was discovered in 1963 at the Centennial Mine. It is named after the locality where it was found. The centennial mine is in Houghton County in Calumet, Michigan. The centennial mine has produced other copper minerals. Calumetite has been found to occur in basalt cavities; as painting in canvas and frescos; and also as corrosive products on bronze items. It is found in association with tremolite, quartz, epidote, monazite, copper, cuprite, atacamite, buttgenbachite, malachite, paratacamite, and anthonyite. Calumet, the locality where calumetite was found was once considered a mining industry. The centennial mine produced approximately 37 million pounds of refined copper before...